September highlights included a Terry Pendleton home run on a September 11 game against the contending Mets as well as a Tom Herr walk-off grand slam against the Mets on Seat Cushion Night. As St. Louis proceeded into the post-season, they found themselves without clean-up hitter Jack Clark, the team's number-one offensive threat. He damaged his ankle when he caught a cleat in the artificial turf at Montreal'sOlympic Stadium.[4] Nonetheless, the Redbirds won 95 games to capture the NL East title.

The Minnesota Twins defeated the Cardinals in seven games. This Series was the first in which the home team won each of the seven games. The Cardinals held their own at Busch Stadium, but the electronically enhanced crowd noise and the "Homer Hankies" in the Metrodome appeared to give the Twins an edge. The booming bats of the Twins were too much for the Cardinals' "inside baseball" style of offense in Games 1, 2, and 6. In Game 7 it was the Twins' pitching that shut down the Cardinals.